Kentucky Lt. Gov. Daniel Mongiardo will again run for the U.S. Senate.

Mongiardo, who lost to Republican Sen. Jim Bunning by 1.4 percent in 2004, announced Monday morning in a news release his intention to file candidacy papers later this week to run in 2010.

Mongiardo was a two-term state senator when he first challenged Bunning in 2004.

Bunning has repeatedly said he will run for another term, but speculation continues that he may back out. Bunning is expected to speak more about his future on Tuesday.

In a statement Monday, Bunning said, "I am gearing up and I look forward to the challenge of taking on whoever comes out of the Democrat primary in May of 2010."

Kentucky Secretary of State Trey Grayson, a fellow Republican, has been mentioned as a possible candidate if Bunning does not seek re-election in 2010.

Along with Mongiardo, state Attorney General Jack Conway has been mentioned as a potential candidate on the Democratic side.

Gov. Steve Beshear put out a statement Monday praising Mongiardo, his 2007 gubernatorial running mate, but Beshear stopped short of endorsing Mongiardo.

In a press release, the governor described Mongiardo as an "outstanding" member of his administration who has been the point person on the development of adventure tourism and improving health care.

"I understand his desire to be part of the national debate on how best to create a more affordable and accessible health-care system for all Americans," Beshear said in his statement.